A conventionally known liquid-cooled-type cooling apparatus for cooling an electronic component comprises a casing composed of a top wall, a bottom wall, and a circumferential wall; a tube disposed in the casing; and inlet and outlet pipes connected to the circumferential wall of the casing, wherein the casing is composed of a box-shaped main body that opens upward and forms the bottom wall and the circumferential wall, and a lid for closing the opening of the main body; through holes are formed in the circumferential wall of the main body; and end portions of the inlet and outlet pipes are inserted into the through holes, and are brazed to the circumferential wall (see Patent Document 1).
However, the liquid-cooled-type cooling apparatus disclosed in Patent Document 1 has a problem in that the formation of the main body of the casing is difficult. In order to solve such a problem, there has been conceived a liquid-cooled-type cooling apparatus which comprises a casing, and fluid flow pipes. The casing includes a casing main body and fluid passage sections provided on the casing main body. The casing main body is composed of a top wall, a bottom wall, and a circumferential wall, and fluid flows through the interior of the casing main body. Each of the fluid passage sections is composed of a base portion extending from the casing main body, and a tubular pipe coupling portion extending from the distal end of the base portion. The fluid flow pipes are inserted into the pipe coupling portions of the casing, and are brazed thereto. The casing of the liquid-cooled-type cooling apparatus is composed of an upper structural member and a lower structural member. The upper structural member forms the top wall of the casing main body, an upper half portion of the circumferential wall of the casing main body, upper half portions of the base portions of the fluid passage sections, and upper half portions of the pipe coupling portions of the fluid passage sections. The lower structural member forms the bottom wall of the casing main body, a lower half portion of the circumferential wall of the casing main body, lower half portions of the base portions of the fluid passage sections, and lower half portions of the pipe coupling portions of the fluid passage sections.
The above-mentioned upper structural member includes a top wall forming portion that forms the top wall of the casing main body; a circumferential wall forming portion that forms the upper half portion of the circumferential wall of the casing main body; base portion forming portions that form the upper half portions of the base portions of the fluid passage sections; semi-tubular coupling portion forming portions that form the upper half portions of the pipe coupling portions of the fluid passage sections; and outward extending portions formed along the lower ends of the circumferential wall forming portion, the base portion forming portions, and the coupling portion forming portions. Similarly, the above-mentioned lower structural member includes a bottom wall forming portion that forms the bottom wall of the casing main body; a circumferential wall forming portion that forms the lower half portion of the circumferential wall of the casing main body; base portion forming portions that form the lower half portions of the base portions of the fluid passage sections; semi-tubular coupling portion forming portions that form the lower half portions of the pipe coupling portions of the fluid passage sections; and outward extending portions formed along the upper ends of the circumferential wall forming portion, the base portion forming portions, and the coupling portion forming portions. The outward extending portions of the upper structural member and those of the lower structural member are joined together, whereby the casing is formed. Simultaneously with mutual brazing of the outward extending portions of the two structural members, the inflow pipe and the outflow pipe are brazed to the corresponding pipe coupling portions in a state in which the pipes are inserted into the corresponding pipe coupling portions formed by the coupling portion forming portions of the two structural members. Notably, portions of the outward extending portions of each of the two structural members, which portions are present on the opposite sides of the coupling portion forming portions are horizontal flat portions which are located on a common horizontal plane.
In general, the above-mentioned upper and lower structural members are manufactured by means of performing press work on a metal blank plate by use of two dies having shapes corresponding to the final shape of the lower structural member. However, in this case, the following problems may occur. That is, when the upper and lower structural members are manufactured in accordance with the above-described method, as shown in FIG. 20, round portions (67) (68) are unavoidably formed at the boundaries between the inner circumferential surface of each coupling portion forming portion (63) (64) of each of upper and lower structural members (61) (62) and surfaces of the corresponding horizontal flat portions (65) (66) formed along the opposite side edges of the coupling portion forming portion (63) (64), the surfaces facing the opposite structural member (62) (61). Accordingly, when the two structural members (61) (62) are joined together, relatively large clearances (72) are formed between the inner circumferential surface of a cylindrical tubular pipe coupling portion (69)—which is formed by the coupling portion forming portions (63) (64) and the flat portions (65) (66) of the two structural members (61) (62))—and the outer circumferential surface of a fluid flow pipe (71). Therefore, the clearances (72) are not filled with a brazing material, and a manufactured liquid-cooled-type cooling apparatus may have leakage of cooling-liquid from the casing. Patent Document 1: Japanese Patent Application Laid-Open (kokai) No. 2005-274120